In a music and audio field, various devices having a point detecting sensor have been proposed to achieve an audio controller with good controllability. For example, a point detecting sensor for producing a DC output voltage corresponding to a location of a pressure point has been proposed by Japanese Patent Laid-Open Publication No. 2000-267663 at pages 3–4 with reference to FIG. 4. When the location of a pressure point is moved in a certain one-dimensional direction (X-direction), such a point detecting sensor produces a DC output voltage indicative of the location of the pressure point,
However, according to this conventional point detecting sensor, signals corresponding to the pressure points can be obtained only on a straight line, namely, on a one-dimensional planar surface of the sensor. Hence, when obtaining the pressure point information of polar coordinates (r, θ) on a circular domain, a structure combined with both an X-axis sensor and a Y-axis sensor are required to create a rectangular sensor even when the information on either the center angle θ or the absolute value r is sufficient.
Further, the structure of the conventional point detecting sensor is complicated because it is necessary to conduct a process for polar conversion. In addition, even when the pressure point information of only the circular domain is sufficient, the rectangular sensor having an X-axis sensor and a Y-axis sensor is required to encompass the circular domain. This results in design related limitations because of many useless parts such as the ones in the vertex areas of the rectangular sensor.